MacIver was never drafted by an NHL franchise and instead took the university route in order to reach the NHL. The defenceman played four seasons with the University of Minnesota Duluth and in 1985-86 was a finalist for the Hobey Baker Award, awarded to the NCAA's top player. While playing at the University of Minnesota, MacIver earned a communications degree and signed as a free agent with the NHL's New York Rangers upon graduation.

He played 500 regular season games in the NHL, scoring 55 goals and 230 assists for 285 points and collecting 350 penalty minutes. A career highlight came during the Ottawa Senators' debut season of 1992-93, when Maciver led the team in scoring with 17 goals and 46 assists for 63 points in 80 games. In the spring of 1996, he scored the final goal in Winnipeg Jets' history prior to the team's relocation to Phoenix in the sixth game of a first round playoff series against the Detroit Red Wings. After retirement he became an assistant coach for the American Hockey League's Springfield Falcons from 2000 to 2003, and then the NHL's Boston Bruins from 2003 to 2006.